Blasting cartridge



F. H. ARMSTRONG BLASTING CARTRIDGE May 3, 1932. l

Filed oct. 7, 1929 2 Sheets-Shea?I l .WNN\\\\\\\\\\\.`

May y3, 1932.

F. H: ARMSTRONG BLASTING cARTRInGE Filed Oct. '7, 1929 2 Sheets-Sheet 2ny/Q 2z/522%@ @w @M wat Patented May 3, 1932 FRANK IBI. ARMSTRONG, OFCHICAGO, ILLINOIS, ASSIGNORKTO SAFETY MINING COM- PANY, 0F CHICAGO,ILLINOIS, A CORPORATION IBLASTING CARTRIDGE Application led October 7,1929. Serial No. 398,043.

This invention relates to blasting cartridges of the general type shownin pending application Serial No. 356,360, filed April 19, 1929. Moreparticularly, the invention is concerned with improvements in theconstruction, mounting and relationships of the valve and electrodeelements of such a cartridge.

An object of the invention is to provide an efficient and reliablecartridge of the character indicated.

Another object of the invention is to simplify and increase thereliability of the valve and electrode elements of blasting cartridgesof the type indicated.

These and other objects are realized by the invention exemplied by thestructures shown in the accompanying drawings.

In the drawings,

Figure 1 is a longitudinal sectional view of one form of constructionembodying my invention.

Figures 2 and 3 are transverse sectional views taken on line 2-2 and 3-3respectively of Figure 1.

Figure 4 is a longitudinal r'sectional view of a second form ofconstruction embodying my invention, and

Figures 5 and 6 are transverse sectional views taken on lines 5 5 and6-6 respectively of Figure 4.

A blasting cartridge of the type to which the present improvements areapplied may consist of a substantially cylindrical body or shell lhaving an internal gas chamber 2 and a discharge opening 3. Thedischarge end ofthe cartridge may be provided with any suitable form ofpressure responsive venting means. The usual form of venting meansemployed in connection with cartridges of this type is a rupturable discpositioned over the open end 3 of the cartridge and held securelythereagainst by means of a shear ring and a discharge cap which hasthreaded connection with the shell body as indicated by 4. The dischargemechanism is not herein shown as it forms no part of the presentinvention.

The opposite end of the gas chamber is deined by transverse wall 5,beyond which extends a sleeve 6. The wall 5 is centrally perforated andan electrode 7 is positioned through this perforation. A flange 8 formedon the electrode is positioned adjacent the outer face of the wall5,'but is insulated therefrom by means of an insulating disc 9. Anannular band of insulating material surrounds the electrode at the pointwhere it passes through the wall 5. The inner end of the electrode whichis positioned within the Oas chamber is provided with screw threadsadaptedto be associated with corresponding threads formed internally ofa heater support 12. Interposed between the inner face of the wall 5 andthe adjacent end face of the electrode 12 is an insulating and packingdisc 11. The heater support is centrally recessed at its free end asindicated at 13 and this recess is provided withr a substantiallyconical approach in order to facilitate the entering of a tubular heaterunit therein. Notches 15 are provided in the end of the heater supportfor the reception of a suitably formed pin wrench vwhich may be used toassemble the heater support upon the electrode and to tighten the sameagainst the packing and insulating disc l1. It will be appreciated thatthe tightening of the heater support serves to draw both the flange 8 ofthe electrode and the heater support toward the interposed wall 5, thuscompressing the insulating and packing elements 9 and 11 whereby toprovide an effective seal against the escape of gas from the chamber.

From Figure l of the drawings it will be noted that the inner end of theelectrode terminates short of the bottom of the pocket formed in theheater support, thereby forming a small chamber between the end face ofthe electrode and the bottom wall of the recess. A gas passage 16extends axially entirely through the electrode and communicates with thesmall gas chamber formed in the heater support. One or-more transverseports are provided in the heater support to place the chamber thereof incommunication with the main gas chamber ofthe cartridge.

Threaded on the outer end of the electrode is a valve body 18 in whichis centrallypositioned an axially adjustable valve stem 19 which has asubstantially conical end for cooperation with a conical seat formed inthe axially toward contacting position.

outer end of the passage 16. Gas may be introduced into the cartridgethrough a suitable passage 2O in the valve body when the valve stem 19is withdrawn from engagement with the valve seat on the electrode andwhen the desired charge has been introduced into the cartridge, thevalve 19 may be moved axially to seal the end of the gas passage 1G,thus trapping the charge that has been formed in the cartridge. Anaperture 21 is provided in the shellbody 1 in transverse alignment withthe aperture 2O in the valve body for the purpose of receiving acharging nozzle. l

It has been found desirable in some types of cartridges to provide ameans whereby the electrode and shell body are normally short circuiteduntil such time as the cartridge is ready to be discharged, in ord-er toprevent accidental discharge by reason of stray currents or theaccidental engagement of the cartridge with exposed Sources ofelectricity. To this end, there is herein shown a short circuitingdevice which consists of a cylindrical sleeve 22 having an inwardlyextending flange adapted to make contact with one or more contacts 23formed ou the valve body. The sleeve 22 has electrical connection withthe shell body through the medium of a coil spring 24 which also servesto move the sleeve The disengagement of this sleeve is effected by thefiring plug 25 which is provided with a sleeve like portion 26 soproportioned that when the plug is inserted inthe end of the cartridgethe sleeve 26 engages the sleeve 22 and moves the same out of engagementwith the contacts 23. The firing plug is provided with lugs 27 whichcooperate with bayonet slots 28 formed in the end of the cartridge bodyto form a detachable connection therewith. A metallic plug 29 isdisposed within a central recess in the firing plug, but is insulatedtherefrom by means of the insulating cup 30. The member 29 is providedwith an axial passage in which an electric conductor may be secured, andin alignment with this passage isl an insulated opening 31 formed in thefiring plug. The circuit between the member 29 and the electrode iscompleted by means of a metallic spring 32 which engages member 29 andthe valve body. A second electric conductor may be secured directly tothe firing plug 25 by means or' the aperture 33 and set screw 34. Thus,one conductor is electrically connected to the cartridge body throughthe medium of the metallic iring plug and lugs 27 thereon which engagethe shell body and the other conductor-is insulated with respect to thetiring plug but is placed in electrical connection with electrodethrough the medium of the metallic plug 29,

the spring 32 and the valve body 18.

The construction shown in Figures 4, 5 and 6 is for the most part thesaine 'as that shown flange formed on said electrode adjacent the" outerface of saidwall, a. heater support in Figures l, 2 and 3, but embodiesa somewhat different type of valve mechanism. In this construction theouter end of the electrode is formed with a cylindrical recess asindicated at 19 and disposed within this recess is the head 19 of avalve stem 20. Stem 2O is screw threaded through the valve body 18which, in turn, is screw threaded on the outer end of the electrode. Thevalve stem is provided with an axial passage 21 which extends from itsouter end to and in communication with a transverse passage 22l locatedshort of the extreme inner end of the stem. rIhe passagev 22 is in.communication with the chamber formed by the head 19 of the stem andthe bottom wall of the cylindrical recess 19" in the electrode. kTheextreme` inner yend 23 of the valve stem is of substantially conicalform for cooperation with a correspondingly formed seat in the end ofthe passage 16.

A nozzle seat 24 is provided intheouter end of the valve stem incommunication ,with the passage 21. With this construction gas may beintroduced axially throughthe valve stem and may pass through theelectrode when the stem is adjusted outwardly to remove the conical end23 thereof from engagement with the electrode. Y

T he construction shown in Figure 4 dii'ers fur-ther from that shown inFigures 1 2`and 3only in that the short circuiting device is in the formof a disc 25 rather than av sleeve with an inwardly extending flange asin Figure 1.

I claimt` Q 1 1. A blasting cartridge comprising a metallic body havingan internal gaschamber formed therein, Aan electrode extending throughan aperture in a wall of said body,a

having threaded engagement with theinner endof said electrode andadapted to serve as .a nut to draw said flange against said wall,

and means for insulating` said electrode from; 'said body. j Y n A 2. Ablasting cartridge comprising ame.-V tallic body having an internal gaschamber formed therein, van electrode extending' through an aperture ina wall ofsaid body,

Van insulating sleeve surrounding said electrode within the aperture, aange formed on said electrode adjacent the outer faceofsaid wall, aninsulating discinterposed between said flange and wall, a nut threadedon the in- -ner end of said electrode and adapted to clamp said flangeand disc against said wall, an insulating disc interposed between theinner face of said wall 'and the adjacent end of said nut, and a heatersupport integral with?V saidnut'. Y 1

3. A blasting cartridge comprising a-metallic body having an internalgas chamber formed therein, an electrode extendingv thru an aperture ina wall :of said body, a flange? 'lok formed on said electrode adjacentthe outer face of said Wall, a heater support having threaded engagementwith the inner end of said electrode and adapted to serve as a nut todraw said flange against said Wall, and means for insulating saidelectrode from said body, communicating charging passages in saidelectrode and heater support, and a valve associated With the outer endof said electrode for controlling the admission of fluid to saidpassage.

4. A blasting cartridge comprising a metallic body having an internalgas chamber formed therein, an electrode extending through a Wall ofsaid body and insulated therefrom, a charging passage extending thrusaid electrode and terminating Within the chamber, a valve cap mountedon the outer end of said electrode, a valve stem adj ustably mounted insaid cap and having a substantially conical tipadapted to engage acorrespondingly formed seat in the electrode, said valve stem having anaxial passage extending from the outer end thereof to a point adjacentthe base of the conical tip, and a transverse passage through said tipin communication with said axial passage.

5. A blasting cartridge comprising a metallic body having an internalgas chamber formed therein, an electrode extending through a Wall ofsaid body and insulated therefrom, said electrode having a chargingpassage extending axially therethrough With a substantially conical seatat the outer end of the passage, the outer end of said electrode beingJformed With an axially disposed cylindrical recess, a valve cap mountedon the outer end of said electrode, a valve stern adjustably mounted insaid cap and having a substantially conical seat, a substantiallycylindrical enlargement formed on said stem adj acent said tip anddisposed Within the aforesaid cylindrical recess, the tipof said stemhaving a transverse passage therethrough opening into said recess and anaxial passage extending from the outer end of said stem andcommunicating With said transverse passage.

Signed at Chicago, Illinois, this 3rd day or October, 1929.

FRANK H. ARMSTRONG.

